This invention relates generally to electrical motor type apparatus and more particularly to electromagnetic apparatus for supporting and/or centering a rotor of an electric motor while at the same time producing rotation and torque of the rotor. The invention, moreover, is directed to a means by which pairs of opposing segments of a brushless DC motor armature are individually commutated and controlled to produce forces which when combined generate forces orthogonal to the rotational axis and/or torques about the rotational axis in any desired direction whereby concentricity of the rotor is maintained and controllable without inhibiting rotation and torque production of the rotor.
While electric motors generally include means for providing rotor suspension and concentricity, such apparatus in the past has relied on external means such as mechanical bearings and bushings. The technique of utilizing magnetic bearings in such apparatus, however, is also known. This type of apparatus has been disclosed, for example, in applicant's prior U.S. Pat. Nos. 3,694,041 and 4,381,875. In both instances control of attractive mode magnetic fluxes was employed rather than by the direct control of armature currents.
Accordingly, it is an object of the present invention to provide an improvement in electrical motors.
It is a further object of the invention to provide an improved electrical motor configuration having reduced decentering forces as well as having lower rotor mass inertia.
It is yet another object of the invention to provide a brushless DC motor having improved means for maintaining rotor concentricity about its rotational axis.
And yet a further object of the invention is to provide an improvement of brushless DC motors wherein a simple configuration of the stator assembly is able to provide both a bearing function as well as a torque producing function of the rotor.